State two ways to produce a higher e.m.f. in an a.c generator.

State (i) two dis-similarities, and (ii) two similarities between a d.c. motor and an a.c. generator.

State two factors on which the magnitude of an induced e.m.f. in the secondary coil of a transformer depends.

Name the device used to transform 12 V a.c. to 200 V a.c. Name the principle on which it works.